Sound absorbing structure



1959 J. J. GRUBER ETAL scum: ABSORBING STRUCTURE Filed Jan. 15, 1957 YFIG.3.

INVENTORS JOSEPH J. GRU BER BY JO EPH J. DeFALCO ORNEYS States SOUND ABSORBING STRUCTURE Application January 15, 1957, Serial No. 634,274

8 Claims. (Cl. 20-4) The present invention relates to sound absorbing structure and more particularly, to a structure formed with the use of building panels wherein the panels serve as a ceiling and roof support or ceiling and floor of a structure, and other panels serve as room partitions and provide acoustical treatment for the ceiling and walls.

It is an object of the present invention to provide a batt of sound absorbing material for insertion into the hollow portion of a metal building panel.

It is a further object of the present invention to provide a batt of sound absorbing material which is larger in cross-section than the hollow portion of the building panel into which it is to be inserted, and after it is inserted by compressing it to a size equal to the crosssection of the panel, will retain its position in the panel by friction resulting from the resilient action of the batt against the walls of the panel.

It is a further object of the present invention to provide a batt of sound absorbing material to serve as a barrier to prevent sound from being transmitted from one room to another in a structure through the nonmovable hollow building panels serving as the ceilings of the rooms.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawing, illustrating a preferred embodiment of the invention, wherein:

Figure l is a view partly in section and partly broken away, showing the acoustical batt used in an acoustically treated metal panel.

Figure 2 is a view of the batt used in Figure 1.

Figure 3 is a view of the batt used in Figure 2 after being compressed.

Referring now to the drawings, there is illustrated at an acoustical treated ceiling panel. The panel has a hat-shaped section 12 which is welded to a flat plate 14 to form a hollow portion 16 in the panel. Apertures 18 allow sound waves to penetrate into the panel to be absorbed by the batt 20 of sound absorbing material. The batt is spaced away from the inner surface of the plate 14 by the integral tapered edge portions providing the legs 22 formed on the batt. The legs space the batt above plate 14 to form a chamber 24 to improve sound absorption. This structure is shown in detail in our copending application Serial No. 634,273. A series of panels (not shown) are interconnected together in a structure with the outer surfaces of the flat plate 14 serving as the ceiling.

A wall partition which may be formed by metal wall panel 30 serves to separate adjacent rooms under the ceiling formed by the flat plates 14. Apertures 32 may be provided to allow the sound to enter and be absorbed by sound insulation material 34.

The panel 10 extends on both sides of the panel or partition 30 and to prevent sound from entering the apertures 18 on one side of the partition, traveling through "atent ice the hollow portion 16 and chamber 24 across the partition and out through apertures 18 on the other side of the partition, the sound barrier in the form of a block 38 is provided.

The sound barrier 38 is placed in the hollow portion 16 of the panel 10 in a position directly over the partition 39 as shown in Figure 1. It is the practice to place the sound barrier in position in the panel prior to installing the panel on the structure. It has been found in past practice that the barrier oftentimes slipped from its position during the handling and installing of the panel so that it did not come directly over the partition in the finished structure. Although the barrier was formed to have a snug fit in the hollow of the panel, due to variations in size of the barrier during forming and variations in size of the hollow portion of the panel, a snug fit Was not always obtained.

In order to obtain a tight fit in the panel the barrier 38 is cut from a batt of bonded fibers having resilient properties. Excellent results have been atttained when the batt is formed of resin bonded glass fibers, preferably from .0001 to .0004 inch in diameter. Phenolic resins have proven to be entirely satisfactory. The resilient properties of the glass fibers are essentially uni-directional which results from the parallel lay-up and horizontal orientation of the fibers during manufacture of the batts as indicated by the lines 42 in Figure 2. The greatest resiliency and strength is in a direction perpendicular to the horizontal orientation of the fibers.

The resiliency of the batt from which the block is cut is also proportional to the density of the fibers in the batt. The more dense the fibers the more pressure required to deflect the batt a given distance. It is found that a batt 9 inches wide, 3 inches deep having a dimension of five inches in a direction perpendicular to the horizontal orientation of the fibers and of a density of 2 /2 pounds per cubic foot requires a total force of four pounds applied uniformly over the top surface in the direction of the arrows 44 in Figure 3, to compress the horizontal layers of the fibers 42 and deflect the batt of an inch. This corresponds to a pressure of about .2.25 pound per square inch. After the load is removed, the material returns to its initial dimensions without any permanent set. Best results are obtained when the batt is from l-4 pounds density (pounds/cubic foot). Beyond this range the batt is less effective either in acoustical properties or ability to hold location.

The barrier or block 38 is made having its width the same dimension as the width of the hollow portion of panel 10 or slightly smaller, and its height or dimension in the direction perpendicular to the horizontal orientation of the fibers greater than the height of the hollow portion of the panel. By exerting pressure in the direction perpendicular to the horizontal orientation of the fibers the height of the barrier may be decreased 2. sufiicient amount to insert it into the panel and into a position which will bring it into a location over the partition, with the lower side of the barrier bearing against the inner surface 46 of the flat plate 14 and the top side of the barrier bearing against the inner surface 48 of the hat-shaped section 14.

The size and density of the barrier or block may be varied to suit conditions under which it is to be used. it is found that a batt having a density of 2 /2 pounds per cubic foot and a requiring pressure of .2.25 pound per square inch to deflect it 4 of an inch, provides enough pressure from resiliency against the top and bottom inner surfaces of the panel to retain it in place without shifting during the handling of the panels during installation on the job, and performs its function of preventing the passage of sound perfectly.

The resilient compressibility of the fibrous block is traceable to the use of resilient fibers bonded together into a cohesive mass. The fibers are laid in parallelism and in parallel strata, for example horizontal, and have a binder distributed throughout to provide for local bonding between adjacent fibers. Such a batt or pad has high resiliency with almost perfect recovery when forces are applied in a direction perpendicular to the planes which contain the fibers. The batt exhibits no appreciable compressibility or resilience when forces are applied in directions parallel to the planes of the fibers.

However, all surfaces of the block appear equally efficient acoustically. Accordingly, the block may be oriented for either vertical or horizontal compression for insertion into the hollow panel.

The weight of the fiber blocks may be varied, but in general it appears that in uncompressed conditions the density should be 14 pounds per cubic foot.

The drawings and the foregoing specification constitute a description of the improved sound absorbing structure in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What we claim as our invention is:

1. In a building construction, an elongated hollow, acoustical panel having a multiplicity of small perforations in a wall thereof, sound absorbing material within said panel and spaced inwardly from said perforated wall to define an elongated chamber therewith, and means for arresting the transmission of sound along said chamber longitudinally of said panel comprising a fibrous resiliently compressible block substantially filling the panel at a point intermediate its ends and between the ends of adjacent sections of sound absorbing material, said block in assembled condition being appreciably compressed to retain said block in firm frictional engagement with inner surfaces of opposed panel walls.

2. In a building construction. an elongated hollow acoustical panel having a multiplicity of small perforations in a wall thereof, sound absorbing material within said panel and spaced inwardly from said perforated wall to define an elongated chamber therewith, and means for arresting the transmission of sound along said chamber longitudinally of said panel comprising a fibrous resiliently compressible block substantially filling the panel at a point intermediate its ends and between the ends of adjacent sections of sound absorbing material, said block in assembled condition being appreciably compressed to retain said block in firm frictional engagement with inner surfaces of opposed panel walls, the fibers of said block being disposed generally in parallel planes extending longitudinally of said elongated panels.

3. An elongated hollow acoustical building panel intended in assembly to extend transversely of a room partition, said panel having a chamber extending from end to end thereof, one wall of said chamber being perforated for the admission of sound energy, elongated sound absorbing members in said chamber spaced from said perforated wall and forming therewith a longitudinally extending passage along which sound may pass, a fibrous bafile block received in said chamber between the ends of adjacent sound absorbent members and located at the junction between said panel and the room partition and substantially filling the chamber at that point, said block being formed of parallel laid bonded resilient fibers and being partially compressed between opposed walls of said chamber to retain its position therein by frictional contact.

4. An elongated hollow acoustical building panel intended in assembly to extend transversely of a room partition, said panel having a chamber extending from end to end thereof, one wall of said chamber being perforated for the admission of sound energy, elongated sound absorbing members in said chamber spaced from said per- 7 forated wall and forming therewith a longitudinally extending passage along which sound may pass, a fibrous bafile block received in said chamber between the ends of adjacent sound absorbent members and located at the junction between said panel and the room partition and substantially completely blocking off the passage at that point, said block being formed of parallel laid bonded rcsilient fibers and being partially compressed between opposed walls of said chamber to retain its position therein by frictional contact.

5. An elongated hollow acoustical building panel intended in assembly to extend transversely of a room partition, said panel having a chamber extending from end to end thereof, one wall of said chamber being perforated for the admission of sound energy, elongated sound absorbing members in said chamber spaced from said perforated wall and forming therewith a longitudinally extending passage along which sound may pass, a fibrous bafile block received in said chamber between the ends of adjacent sound absorbent members and located at the junction between said panel and the room partition and substantially filling the chamber at that point, said block being formed of parallel layers of bonded resilient fibers and being partially compressed between opposed walls of said chamber to retain its position therein by frictional contacts, the layers of fibers being parallel to the length of said panel and perpendicular to the line of action of the compressive force effective on said block.

6. An elongated hollow acoustical building panel intended in assembly to extend transversely of a room partition, said panel having a chamber extending from end to end thereof, one wall of said chamber being perforated for the admission of sound energy, elongated sound absorbing members in said chamber spaced from said perforated wall and forming therewith a longitudinally extending passage along which sound may pass, a fibrous baffie block received in said chamber between the ends of adjacent sound absorbent members and lo cated at the junction between said panel and the room partition and substantially completely blocking off the passage at that point, said block being formed of parallel layers of bonded resilient fibers and being partially compressed between opposed walls of said chamber to retain its position therein by frictional contact, the layers of fibers being parallel to the length of said panel and perpendicular to the line of action of the compressive force effective on said block.

7. An elongated hollow acoustical building panel adapted in assembly to extend transversely of a room partition, said panel having a chamber extending from end to end thereof along which sound may pass, one wall of said panel being perforated for the admission of sound energy, a battle block in said chamber in position to prevent transmission of sound along said chamber across the room partition, said block being composed essentially of resilient fibers lightly bonded together to provide rcsilient compressibility, said block having a first normal dimension before compression which is greater than one transverse dimension of said chamber and having a second dimension transverse to its said first dimension which is substantially equal to the other transverse dimension of said chamber, said block thereby substantially completely filling said chamber, the resilience of the block as compressed in said chamber renders said block movable longitudinally of said chamber to desired position and effective to retain it in such position by friction.

8. The structure as defined in claim 7 in which the fibers of said block are disposed generally in parallel planes extending perpendicular to the direction of the line of action of the force applied to compress said block for insertion in said chamber.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Kilmer Jan. 17, 1933 Voight Mar. 9, 1937 Ross et a1. Apr. 20, 1937 Johnson Sept. 5, 1939 Taforo Sept. 5, 1944 6 Park Oct. 12, 1948 Gonda Oct. 31, 1950 Bush June 17, 1952 Peterson Jan. 17, 1956 OTHER REFERENCES Scientific American, pages 155-156, September 1945. 

